In the mass production of prefinished moldings, which term is here intended to include any elongated element from a small bead to a wide plank, it is standard to pass the molding longitudinally through a chamber in which it is given a smooth coating of the desired finish which can be paint, varnish, or the like. Such a coating machine normally has a closed treatment chamber through which some sort of transport device passes the moldings one after the other. An atomizing device generates a mist of the coating liquid in the chamber and a vacuum pump maintains the chamber at subatmospheric pressure so that the mist can be recycled and so that it does not escape to pollute the surroundings with the often toxic volatile solvents being used. Such an arrangement applies an extremely smooth and uniform coating of liquid to the molding being treated, whether it is of wood, metal, plastic, or like material.
A major disadvantage of these devices is, however, that all surfaces of the molding are coated. On the one hand this represents a waste of the often costly coating liquid, since at least one surface of such a molding is normally never intended to be seen so coating it serves no purpose. On the other hand coating all surfaces of the molding creates a handling problem, since the still-liquid coating on the underside of the molding comes off on the downstream conveying devices. In addition if the back of the molding has been accurately milled to fit, for example, a given inset in a picture frame, the coating can change these dimensions and reduce detail, the latter being a particular problem when the molding is shaped with fine grooves adapted to receive special clips.